/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     struct TreeNode *left;
 *     struct TreeNode *right;
 * };
 */

struct TreeNode* trimBST(struct TreeNode* root, int low, int high) {
    if (!root) {
        return root;
    }
    if (root->val < low) {
        return trimBST(root->right, low, high);
    }
    if (root->val > high) {
        return trimBST(root->left, low, high);
    }
    root->left = trimBST(root->left, low, high);
    root->right = trimBST(root->right, low, high);
    return root;
}
